Research by Swansea University academic Dr Dan Eastwood, published in the current issue of the prestigious Science journal, sheds new light on how the evolution of fungus impacted on the formation of coal deposits, the advent of the ice age and the coming of the dinosaurs.

In his paper, The Paleozoic origin of enzymatic lignin decomposition reconstructed from 31 fungal genomes, Dr Eastwood of the College of Science joined with researchers from around the world to carry out a comparative study of 31 fungal genomes focusing on when the ability to decompose wood by higher fungi first evolved. Dr Eastwood knew that wood is extremely tough as it is a complex composite of three main polymers, cellulose, hemicellulose and lignin. The close binding of these polymers and the complex nature of lignin means that wood is resistant to decay.

This research investigated when fungi evolved the ability to breakdown lignin by focussing on the enzymes primarily responsible for lignin decay, called peroxidises. The ability to breakdown wood gave these fungi an advantage to spread and diversify all over the world giving us the mushroom-forming species we see in woodlands and supermarkets.

Dr Eastwood said: “When plants ruled the earth and wood first evolved in vast coastal swamps during the Carboniferous period (360 – 300 million years ago (MYA)) there was no effective biological mechanism of wood decay. This led to massive depositions of coal and a reduction of CO2 in the atmosphere as carbon was locked up in the plant material. This in turn was thought to be the main reason for the cooling and ice age associated with the Devonian, Carboniferous and Permian periods.

“Our research suggests that the evolution of wood decay in fungi was a factor in the loss of coal deposits, the rise in atmospheric CO2 during the Permian, and the gradual warmer and drier conditions which led to the age of the dinosaur. Today fungi continue to play a major role in the carbon cycle on land – converting plant matter back into CO2.”